It took me a long time to understand what he was trying to tell me. 'You don't mean defect, Frank?'

'Letting Stinnes slip through our hands will be no solution,' said Frank. He gave no sign of having heard my question. 'Because after Stinnes there will come another and after that another. Not perhaps as important as Stinnes but contributing enough for Coordination to put the pieces together.' His voice was soft and conciliatory as if he'd rehearsed his piece many times.

I swung round to see him. I was all ready to blow my top but Frank looked drained. It had cost him a lot to say what he'd said and so despite my anger I spoke softly. 'You think I'm a Soviet agent? You think that Stinnes will blow my cover, and so I'm deliberately obstructing his enrolment? And now you're advising me to run? Is that it, Frank?'

Frank looked at me. 'I don't know, Bernard. I really don't know.' He sounded exhausted.

'No need to explain to me, Frank,' I said. 'I lived with Fiona all those years without knowing my own wife was a Soviet agent. Even at the end I had trouble believing it. Sometimes I wake up in the middle of the night and I think it's all a nightmare, and I'm relieved it's all over. Then as I become fully awake I realize that it's not over. The nightmare is still going on.'

'You must get Stinnes. And get him soon,' said Frank. 'It's the only way that you'll prove to London that you're in the clear.'

'He'll freeze if he's hurried,' I said. 'We've got to let him talk himself into coming. There was an old man who used to live up in Reinickendorf. He was a swimmer who'd been a competitor in the 1936 Olympics but he'd lost a foot to frostbite in the war. He taught a lot of the kids to swim. One year I took my son Billy to him and he had him swimming in no time at all. I asked him how he did it, because Billy had always been frightened of the water. The old man said he never told the kids to go into the water. He let them come along and watch the others. Sometimes it took ages before a child would summon up the courage to get into the pool but he always let them make their own decision about it.'

'And that's what you're doing with Stinnes?' Frank came back to his desk and sat down.

'He'll have to break a KGB network to prove his bona fides, Frank. You know that, I know it, and he knows it too. Stop and think what it means. He'll be turning his own people over to us. Once a network breaks, there's no telling how it will go. Scribbled notes, a mislaid address book or some silly reply to an interrogator and another network goes too. We both know the way it really happens, no matter what the instruction books ordain. These are his people, Frank, men and women he works with, people he knows, perhaps. He's got to come to terms with all that.'

'Don't take too long, Bernard.'

'If London hadn't meddled by making the big cash offer we might have him by now. The cash will make him feel like a Judas. Mentioning the cash too early is the most stupid thing we could do with a man like Stinnes.'

'London Central are trying to help you,' said Frank. 'And that's the worst thing that can happen to any man.'

'It's taking a longer time than usual because we went to him; he didn't come to us. Those idiots in London are trying to compare Stinnes to the sort of defector who comes into West Berlin, picks up a phone and says, let's go. For them you just send a military-police van and start on the paperwork. Stinnes hasn't been nursing this idea for years and waiting for a chance to jump. He's got to be tempted; he's got to be seduced. He's got to get accustomed to it.'

'Surely to God he knows what he wants by now,' said Frank.

'Even after he's decided, he'll want to put his hands on a few documents and so on. It's a big step, Frank. He has a wife and a grown-up son. He'll never see them again.'

'I hope you don't adopt this maudlin tone with him.'

'We'll get him, Frank. Don't worry. Is there anything else you wanted to talk about?'

Frank stared at me before saying, 'No, I just thought it appropriate to tell you personally about the death of your man MacKenzie. The department are keeping it all very low-key.'

'I appreciate it, Frank,' I said. The true reason for the meeting – the suggestion that I might want to walk through Checkpoint Charlie and disappear for ever – was now a closed book, a taboo subject that would probably never be mentioned again.

The door opened as if by magic. I suppose Frank must have pressed some hidden signal to summon old Tarrant, his valet and general factotum. 'I appreciate it very much, Frank,' I said. He'd risked what was left of his career, and a magnificent pension, to fulfil the promise he'd made to my father. I wondered if I would have shown such charity and confidence to him had our positions been reversed.

'Tarrant, tell the driver that my guest is leaving. And have his coat ready, would you?' said Frank.

'Yes, sir,' said Tarrant in loud sergeant-major style. After Tarrant had gone marching off along the hall, Frank said, 'Do you ever get lonely, Bernard?'

'Sometimes,' I said.

'It's a miserable affliction. My wife hates Berlin. She hardly ever comes over here nowadays,' said Frank. 'Sometimes I think I hate it too. It's such a dirty place. It's all those bloody coal-fired stoves in the East. There's soot in the air you breathe; I can taste it on bad days. I can't wait to get back to England. I get so damned bored.'

'No outside interests, Frank?'

His eyes narrowed. I always overstepped the mark with Frank but he always responded. Sometimes I suspected that I was the only person in the world who talked to him on an equal footing. 'Women, you mean?' There was no smile; it was not something we joked about.

'That sort of thing,' I said.

'Not for ages. I'm too old for philandering.'

'I find that hard to believe, Frank,' I said.

Suddenly the phone rang. Frank picked it up. 'Hello?' He didn't have to say who he was; this phone was connected only to his private secretary here in the house. He listened for a time and said, 'Just telex the usual acknowledgement and say we're sending someone, and, if London want to know what we're doing, tell them that we are handling it until they give instructions otherwise. Phone me if anything develops. I'll be here.'

He put the phone down and looked at me. 'What is it?' I asked.

'You'd better close the door for a moment, while we sort this out,' said Frank. 'Paul Biedermann has been arrested by a security officer.'

'What for?'

'We're not exactly sure yet. He's in Paris, Charles de Gaulle airport. We've just had it on the printer. The signal said "Mikado" and that's a NATO code word for any sort of secret documents.'

'What's it got to do with us?' I said.

Frank gave a grim smile. 'Nothing, except that some bloody idiot in London has given Biedermann a "sacred" tag. At present no one in London is admitting to it, but eventually they'll find out who authorized it. You can't put a tag on anyone without signing the sheet.'

'That's right,' I said. I suddenly went very cold. I was the idiot in question.

Frank sniffed. 'And if Biedermann is carrying stolen secret papers while getting protection from someone in London there will be a hell of a row.' He looked at me and waited for my response.

'It doesn't sound as if he got much protection. You said he was arrested.'

'A spot check. No tag could save him from a spot check. But people with 'sacred' tags are supposed to be under some sort of surveillance, no matter how perfunctory.' He smiled again at the thought of someone in London getting into hot water. 'If he's got NATO secrets, they'll go mad. Do you know Paul Biedermann?'

'Of course I do. We were both on that cricket team you tried to get going for the German kids.'

'Cricket team. Ah, that's going back a long time.'